The invention relates to the analysis of liquid samples with a spectrometer or photometer or other optical measuring devices. Such analyses take place typically, but not exclusively, in molecular biological, biochemical, inorganic chemistry, organic chemistry and food chemistry laboratories. Samples are analyzed optically e.g. in research, diagnostics and quality control. They are analyzed e.g. by means of absorption, reflection, emission, fluorescence, Raman or luminescence spectroscopy in the UV-VIS or IR wavelength range. Examples for analytes to be measured are biomolecules like nucleic acids, proteins, lipids as well as inorganic or organic substances and compounds. These analytes can be measured directly or after a chemical reaction, which serve to facilitate spectrometric or photometric analysis.
The invention relates in particular to all exemplary applications. An important area of application is the measurement of valuable samples in small amounts in molecular biology. In many cases, only small sample amounts (e.g. below 1 to 5 microliters) are available because no more material can be obtained. Thinning of the samples would lead to measurement results that are too inaccurate due to reduced absorptions. A typical application is the photometric or fluorometric measurement of nucleic acid concentrations before a PCR or real-time PCR in order to be able to use them for the PCR optimal output amount of the nucleic acid. Another example is the measurement of the concentration of nucleic acids and marker substances built into the nucleic acids and the marking density derived from it in the case of marked nucleic acids, in order to be able to use the optimal amount of the marked nucleic acid before the start of a microarray experiment and to be sure that the marking density of the nucleic acid lies in the optimal range.